Right now I have a HD that is an Ultra 100 hookup. I recently purchased a bigger HD that is a Ultra 133. Should I slave the 133 to the 100 or should I master the 133 and the 100. I have 2 IDE ports open on the motherboard.
The difference between a 133 HDD with one with bus 100 is marginal.So you've to decide according to their capacities and your preference(If I were you ,I would consider the new for my apps (so the slave one)and the old one for my system,so the master).That's my 2 cents.
like what Aryajan79 said, the speed difference is small.
set your existing ATA100 drive to master, set the new drive to slave, plug them both into the same IDE channel & enjoy.
Avoid putting a HD and CD drive on the same channel as this slows the HD down a lot.